Innholdsfortegnelse for August - September 2015 i Australian Sky & Telescope

As I write this, two days after New Horizons’ historic fly-by of the Pluto system, I can’t help but feel a sense of sadness mixed in with all of the exhilaration and wonder. For this will almost certainly have been the last exploration of a major Solar System body in my lifetime. Why? Well, for a start, we know that there are no more planets within the orbit of Neptune. Sure, there are thousands of Kuiper Belt Objects further out, but they’re all probably pretty much like Pluto. If there’s another large body out there to be discovered, it’s going to be much farther out — and astronomers have good reason to think it would have to be at least three times Pluto’s distance from the Sun. But let’s say…

NASA’s NuSTAR mission has detected an unexpected haze of high-energy X-rays in our galaxy’s crowded centre. Kerstin Perez (Columbia University) and colleagues found the X-rays emanating from within our galaxy’s central 10 light-years or so, they report in the April 30 issue of Nature. In and of themselves, X-rays from the galactic centre aren’t unusual. But the X-rays NuSTAR detects don’t seem to be associated with structures already known to exist, such as the supernova remnant Sgr A East or the dust and gas clouds of Sgr A West that are falling toward the supermassive black hole. Instead, the team proposes that thousands of dead stars could be responsible for the high-energy X-rays: massive (and still-growing) white dwarfs, spun-up pulsars, or black holes and neutrons stars feeding on low-mass companion…

Is there, or has there ever been, life on Mars? The question has been posed many times over the centuries. Many a science fiction story has been built on the premise that Mars does have life, and ongoing scientific investigations using both spacecraft in orbit and landers on the surface have sought whatever evidence is available. It now appears that conditions were once amenable to life, albeit primitive, with indications that the apparently bone-dry planet was once much wetter and had a thicker atmosphere. That of course is not proof that there was life, just that it was possible. A few decades back intriguing evidence turned up in an unexpected place, namely on the icecap of Antarctica. It took the form of a meteorite, one of some 7,000 gathered by…

Under a Floridian sky, three astronauts boarded their metallic spacecraft. As throngs of well-wishers nervously looked on, at the awaited moment the crew blasted up, up into the warm, clear air — soaring toward the Moon. Flying where no human had gone before, they approached the cratered lunar surface, orbited around the silvery orb and beheld the farside of the our natural satellite. Then the spacecraft returned to Earth and plunged into the Pacific Ocean, where an American naval vessel gathered the intrepid astronauts and carried them safely back to the United States to be welcomed as national heroes. This is the true story of the Apollo 8 mission, during which three American astronauts circumnavigated the Moon in December 1968. It also happens to be the plot of Jules Verne’s…

An observing friend of mine has a particular fondness for what he calls ‘pizza objects.’ These are celestial two-for-one deals — a pairing of targets lying in the same field of view. Two objects for the effort of finding one. And if they’re different from each other, so much the better — variety is the spice of life! So in his honour, let’s enjoy a two-for-one binocular field northwest of the star Antares that gives us an easy triple star and a much more challenging globular star cluster. The triple star is Rho (p) Ophiuchi. It might just be the most famous star you’ve never seen. In long-exposure photographs of the region, Rho is surrounded by a colourful fog of nebulosity. Indeed, the Rho Ophiuchi Nebula is so well-known that…

This issue’s doubles are in the southwest corner of Sagittarius, and not near the Milky Way. With no bright guide stars and only a few stars of 4th and 5th magnitude, the use of Go To systems, or setting circles, makes for easier finding than star-hopping. Even so, our targets can be found with optical finders of 50-mm and a good star map. All of them are 19th century discoveries, four of them by John Herschel from his southern sky survey of the 1830s. Starting with the most northerly, the attractive multiple star HJ 5188 (old-style, h 5188) is a John Herschel discovery from 1834. An 18-cm refractor at 100› showed a bright white star (A) with a well-separated magnitude-7.5 companion (C), and a much closer magnitude-10 star north-east (B);…

On moonless nights away from the glow of outdoor lighting, the misty trail of the Milky Way stretches across the sky through Sagittarius. Its gossamer glow is fashioned from remote swarms of innumerable stars, and the silvery splendour of their intermingled light shows us the plane of the disk-shaped, spiral galaxy in which we live. For the most part, the stars that lie along this section of the Milky Way, as well as the dark clouds that decorate it, lie within the Sagittarius-Carina Arm of our galaxy. This is the next spiral arm inward from ours, and it blocks the view beyond. The Sagittarius Milky Way is interlaced with dark rifts, however. Within one dark rift, a gap allows us to peer deeper into the galaxy. The stars that shine…

Most home-built scopes are variations on existing designs, but through little tweaks and additions become something unique. Michael Wolfson’s 37.5-cm Newtonian reflector is a fine example. “After acquiring many telescopes while searching for the sweet spot between portability and performance, I concluded that an ultra-light Dobsonian was the way to go” Michael says. He wanted the greatest aperture with the least weight, in a scope that he could use without a ladder or step stool. Albert Highe’s book, Engineering, Design and Construction of Portable Newtonian Telescopes, which details building highly portable large-aperture scopes, was one source of inspiration and ideas. Michael had also seen a single-strut Newtonian at a star party, which prompted him to build several smaller versions to gain experience. So when he acquired a 37.5-cm f/4.6 quartz…

It was four years ago that Cathi Humphrey-Hood and I started planning for the March 20, 2015 total solar eclipse, which would be visible from the far north of the planet. After first deciding to go to the Faeroe Islands for witness it, further research indicated there was a marginally (and I mean minutely marginal) better chance of good weather in Svalbard, so we opted for the latter archipelago, well inside the Arctic Circle. Joining us on the trip were David and Wendy Bevan, Rob Lucas, Helen Robinson and Cathi’s children Elswyth and Aengus. Of course a visit to this part of the world in March meant that aurora hunting was also going to feature, so we planned a trip to encompass the Norwegian mainland as well as Svalbard. After…

Queensland Astrofest August 7-16 Annual star party qldastrofest.org.au National Science Week August 15-23 Lots of public astronomy activities held around Australia scienceweek.net.au World Record Stargazing August 21 Mt Stromlo Observatory leads two world-record stargazing efforts rsaa.anu.edu.au/world-record-stargazing StarFest 2015 October 2-4 Held at Coonabarabran, home to Siding Spring Observatory, there'll be three days of activities during the Festival of the Stars starfest.org.au Siding Spring Open Day 2015 October 3 Australia's largest optical observatory throws open its doors to the public starfest.org.au Border Stargaze October 8-11 Amateur astronomy star party near Albury on the NSW-Vic border asaw.org.au/bsg VicSouth Desert Spring Star Party November 6-9 Annual star party hosted by the astro societies of Victoria and South Australia vicsouth.info National Australian Convention of Amateur Astronomers March 25-28, 2016 Held every second year, the…

New evidence suggests that nanoflares, small but potent bursts of energy, might heat the Sun’s outer atmosphere. But the evidence is still up for debate. For decades, scientists have struggled to understand why the Sun’s outer atmosphere, known as the corona, is a blistering-hot few million degrees when its visible ‘surface ’ the photosphere, bubbles away far below at only thousands of degrees. Ideas range from waves rippling along magnetic field lines to field lines twisted so tightly they snap, releasing tremendous amounts of energy. There’s also another question to answer: is the heating process steady, or does it occur in explosive bursts? These bursts would be small stuff — they release only a billionth the energy of regular flares, and they d be too small, quick and faint for…

One benefit of binoculars is their big-picture view. Take the Moon. Looking at it with only 8 or 10 power makes you focus on larger issues, such as why did the second-quarter (waxing gibbous) Moon get the oceans with the ominous names? And what’s that gulag of ancient Greek astronomers doing, shivering on the shores of the Sea of Cold? Why are the crater names beginning with Al- so concentrated in the south? And why was the great Galileo assigned such an insignificant little out-of-the-way crater that you need 20Ч to spot it? The man to ask, the man with the plan, the man who named all the major features on the Moon, was the Italian Jesuit astronomer Giambattista Riccioli (1598–1671). Riccioli published his landmark Moon map in 1651, just…

This column is normally dedicated to the stars and constellations. But the stars do cohabit the night sky with other celestial bodies, and there's one such nighttime object that radically affects the visibility of stars. It is, of course, the Moon. It's all about star-people versus Moon-people. This sounds like a conflict in a B-grade science-fiction movie — but the question is how do you see yourself: as a star-person or a moon-person? Do you enjoy exploring all the details of the brightest satellite in the Solar System? Or do you like to travel and revel in the starry universe? Most of us, of course, enjoy both lunar and stellar observing. But bright moonlight can make for a frustrating experience for would-be stellar and deep sky observers. So let’s get…

In the realm of deep-sky imaging, single-shot colour cameras have long played second fiddle to their monochrome cousins paired with colour filters. While monochrome cameras are generally more sensitive and produce the best results, the difference isn’t so obvious anymore. Today’s one-shot colour cameras, combined with the latest processing software, can produce stunning astrophotos that rival the best, typically with a lot less money and time spent. What is one-shot colour? One-shot colour (OSC) cameras are actually monochrome sensors with one important addition. Unlike a monochrome detector, OSC sensors are covered with a microscopic grid of filters known as a Bayer matrix, named for its inventor, the late Dr Bryce Bayer. This grid places a red, green or blue filter over each individual pixel. When an exposure is made, the…

In their effort to understand the unseen matter that holds spinning galaxies together and forms the skeleton of cosmic structure, astronomers are trying to determine how much this dark matter interacts with itself. The answer seems to be: not much. Weakly interacting massive particles (WIMPs), physicists’ most popular dark particle candidate, are downright antisocial — they glide right past one another. But in simulations, slippery dark matter particles pool too easily, creating deep gravitational wells in which galaxies crowd more densely than observed out in the real universe. One way to overcome the pooling problem is to make dark matter less slippery. In alternative models, so-called ‘hidden-sector’ dark matter particles make contact, explains Jonathan Feng (University of California, Irvine). Many of these models have the added benefit of explaining a…

Astronomers have discovered 195 compact elliptical galaxies, upping the known number of these weird objects sixfold. These dwarf galaxies are puny balls of old stars, each having maybe a few billion solar masses. Most come in clusters, and observers have found debris around some, suggesting that they were once larger but had their outer edges ripped from them by other galaxies. But a couple sulk all by themselves, making the tidal disruption theory problematic: if there’s nothing around to strip material off these galaxies, did they really shrink? In the April 24 issue of Science, Igor Chilingarian (Smithsonian Astrophysical Observatory) and Ivan Zolotukhin (Moscow State University, Russia) report their discovery of 195 of these objects, with 56 in clusters, 128 in galaxy groups and 11 in isolation. Given the galaxies’…

I spent the end of 2014 squirming. For months Id been waiting for the release of the full-mission data from the European Space Agency’s Planck spacecraft. Planck launched in 2009 to study the cosmic microwave background (CMB), the relict radiation from the universe’s birth. It’s the latest advance in a field fairly young by astronomical standards: 50 years ago this month, Bell Labs’ Arno Penzias and Robert Wilson published their landmark detection of the CMB. The 1965 paper, “A Measurement of Excess Antenna Temperature at 4080 Mc/s” in the Astrophysical Journal, is less than two pages long. Only two paragraphs talk about the “unaccounted-for antenna temperature” Penzias and Wilson had stumbled upon, and the authors politely leave suggestions for its origin to a companion article by Robert Dicke and others…

DELITE-FUL VIEWS Tele Vue’s DeLite series eyepieces provide a generous 62° apparent field of view with comfortable eye relief of 20 millimetres. These 1?-inch oculars are based on the advancements of the company’s popular Delos series, in an economical and lightweight body. Available in 18.2-, 11- and 7-mm focal lengths, each features a unique, extendable twist-lock eye guard. The DeLite eyepieces are parfocal with others in the series, as well as Tele Vue’s 1›-inch Plossl, Panoptic, Nagler and Delos eyepieces, and accept its Dioptrx correctors. televue.com  and local dealers DEEP SKY COMPENDIUM Publisher Willmann-Bell announces Annals of the Deep Sky: A Survey of Galactic and Extragalactic Objects by Jeff Kanipe and Dennis Webb. The series promises to be the most up-to-date and comprehensive observing guide available today. Each richly illustrated…

Mercury returns to our evening skies in August, low down on the western horizon but slowly climbing higher as the month progresses. And it won’t be alone – Jupiter and Venus will be nearby, as will the star Regulus on August 7 and the crescent Moon on the 16th. Moving into September, Mercury will appear close to the star Spica, before sliding back down towards the horizon and the Sun’s glare. Look for the Moon nearby on September 15. As mentioned, Venus will be low on the western horizon after sunset at the beginning of August, but will be lost in the glare of the Sun by mid-month as it slides between us and our star. But don’t worry, it will be back at the end of the month, this…

The realisation in the late 1940s that the Moon’s dark, circular maria exist within very large impact craters (called basins) was profoundly important. Excavated during titanic impacts, these big, deep holes threw their ejecta widely across the Moon, later became filled with mare lava flows, and eventually developed concentric fractures and mare ridges as they subsided. Basins are thus the most important lunar landforms. When observing the Moon, your eye is drawn to the major lava-filled basins such as Imbrium, Crisium, Humorum and Nectaris, but numerous smaller ones are often overlooked. A powerful tool that has helped geophysicists recognise basins is the global gravity map created by NASA’s Gravity Recovery and Interior Laboratory (GRAIL) orbiters, twin craft that circled in tandem at low altitude before crashing onto the lunar surface…

Ronald Stoyan and Stephan Schurig Oculum-Verlag GmbH and Cambridge University Press, 2015 Desk Edition, 264 pages, ISBN 9781107503380 Field Edition, 264 pages, ISBN 9781107503397 Is there a future for paper star charts in an era of computers and hand-held electronic devices? Cambridge University Press and German publisher Oculum-Verlag seem to think so. They’ve collaborated to produce an English-language version of the interstellarum Deep Sky Atlas, which has been available in German since late 2013. It’s the most ambitious star atlas in many years and one of the most innovative ever. Viewed in daylight, the atlas is gorgeous. It comes in two different editions with identical contents. The Desk Edition is printed on high-quality paper, while the Field Edition is printed on synthetic paper that’s waterproof, light and tough. Facing pages…

August 2005 First pictures of exoplanets? On April 27, 2004, a European/American imaged the dim brown dwarf 2M 1207, revealing an extremely faint, red blip just 0.78 arcsecond from it. “We understood essentially immediately that we had a very strong exoplanet candidate” says Ben M. Zuckerman (UCLA). In January 2005 Glenn H. Schneider (U. Arizona) presented Hubble observations that essentially confirmed that the star and its companion have common motion across the sky, a very strong indication that they are gravitationally bound. Aug/Sep 2010 Stars are not born equal With masses tens of times that of the Sun and with light outputs millions of times higher, the largest stars hold the power of life and death. They destroy protoplanetary disks and trigger the birth of other stars. And after their…